Spring counterbalancing means for the covers of cabinets



May 19, 1953 c. B. ULRICH 2,639,053

SPRING COUNTERBALANCI NG MEANS FOR THE COVERS OF CABINETS Filed Jan. 27, 1950 INVENTOR. CHARLES E. ULRICH ATTORNEY Patented May 19, 1953 SPRING OOUNTERBALANCIN G MEAN FOR THE COVERS OF CABINETS Charles B. Ulrich, Jamestown, N. Y. ApplicationJanuary 27, 1950, Serial No. 146,895

4 Claims. (01. 217-60) The invention pertains to counterbalancing means for the hinged covers of vertical planfiles and the like, which covers are so large and heavy as to be diificult to operate unless a considerable part of their weight is counterbalanced in one way or another.

In the past, it has been proposed to effect such counterbalancing by means of counterbalancing weights, but this practice, although operative, was objectionable for two reasons: first, the weight to be effective, necessarily was required to have sufficient mass to develop by the. action of gravity, the maximum counterbalancing force required, and said mass was a constant quantity always producing by gravitythe same weight, although the gravity moment of the cover to be counterbalanced varied from zero to a maximum value determined by the weight of the cover in any particular case, and considerable complica-' tion resulted from attempting to give-the counterbalancing moment a varying value similar to the varying value of the gravity moment of the cover; second,- the weight of the counterbalancing' mass being constant, it was necessary to construct the supporting means for the counterbalancing mechanism not only strong enough to safely withstand the counterbalancing forces, but in addition, strong enough to at all times safely support the counterbalancing weight, and this added substantially to the weight of the cabinet having the counterbalanced cover.

It is an object of this invention to eliminate the difficulties incident to the use of weights for counterbalancing hinged covers of the class re ferred to, by using spring counterbalancing means for that purpose; it is a further object of the invention to produce a, counterbalancing means for such hinged covers. in which the counterbalancing forces are produced by springs'having small weight in comparison with said forces; it is a further object of the invention to produce spring counterbalancing means for'such covers, in which counterbalancing moment, is substantially pro-' portional to the corresponding variations in the gravity moment of a cover during its opening and closing movements; and it is a further object of the invention to limit cover opening movement by the structure of the spring counterbalancing means.

for example by pins as indicated in Fig. 2.

The invention will preferred embodiments thereof, in which I Fig. 1 shows in side elevation a verticalplanfile with its hinged cover. in open position, and with spring counterbalancing'mechanism of the invention, supported by the side wall of the cabinet of the planfile, v I

Figs. 2 and 3 are horizontal, sectional views to an enlarged scale of parts of the structure shown in Fig. 1 taken respectively along the lines 2-2 and 3-3 in Fig.1,

Fig. 4 is a sectional view to a further enlarged scale, of the structure'shown in'Fig. 3, taken along the line 4-4 in Fig. 3, and

Fig. 5 is a sectional view of the structure shown I in Fig. 2 taken along the line 5'5 in Fig. 2, this view being Fig. 4.

Similar numerals refer to similarv parts throughout the several views. a

As shown in Fig.1, the-cabinet l0 has'mounted on the outer surface of one :of its side walls, a mounting plate 58 to which a-cylindrical casing 59 is rigidly secured. Said casing contains a spiral spring 60 having its outer end secured to said casing, and having its inner end secured to a cylindrical hub: 6| supported by a shaft "extending through the outerside wall of said casing (see Fig.- 2). Outside of the casing 59, the shaft 62 carries and has rigidly secured thereto a pinion gear 63, said shaft extending beyond said gear to substantially the same scale as I and having a squared end "6211 to facilitate spring adjustment. The hub 61 and gear 63 are rigidly secured to the shaft 62 in any convenient manne As shown-in Fig. 1, the gear 63 is in meshwith a curved rack bar or link pivotally connected at its upper end at 65 with an end surface of the v cover l3 hinged to the cabinet at [4. The rack bar 64 extends a substantial distance below the gear 63 fora purpose below described. To impart the required stiffness and strength to the rack bar 64 to carry the cover load that it may berequiredto support, said rack bar is provided with a longitudinal web 64a opposite its toothed surface, the outer edge of said web being parallel with the pitch line'of the teeth of said rack bar, for engagementwith a grooved roller '66, (Fig. 2), which roller is supported on a bearing 'rod 61 having end bearing surfaces supported for rotation'inthe side legs of a U -'shapedmounting 'member 68 secured to and rigidly supported by .the spring casing 59. Therod 61 is rigidly secured to the roller 66 in any convenient manner,

be best understood by ref- 1 erence to the accompanying drawings illustrating for example, by a pin as indicated in Fig. 2, and the ends of said rod are mounted in horizontal slots 69 in the side legs of the mounting member 68, said slots being in substantially horizontal alignment with the shaft 62 and being so positioned that when the rod 61 is held in the right hand ends of said slots, the roller 56 will hold the teeth of the rack bar 64 positively in mesh with the teeth of the gear 53 and prevent disengagement of the rack'bar from the gear; however. as shown in Fig. 5, the teeth of the rack bar 64 and of the gear 63 are of substantial size to carry the load upon them which may be large for large covers, and said teeth are preferabiYma'dewith a substantial radial clearance when in their properly meshed or load-carrying relation, and, furthermore, said teeth are constructed with a substantial angular clearance or backlash, to the end that the rack bar may be operative for substantial changes in its angle of inclination to -thegear, which may result from the curvature of different portions'of the rackbarfand that'b'inding'of the angle of inclination. r

Therod 61 is held in the right hand ends of the slotslildurin' the operation or the counterbala'ncing structure, by pins extending across said slotsywhen' the pins 18 are removed, theleng'th of the slots 69 permits movemento'f 'the roller '66 and rack bar 64 away from the gear sufficiently to'disengage the rack b'ar'from the gear,- thereby permitting "adjustment of the strength of the spring 60 by means of a wrench or lever on the teeth willnot occur throughout therang eofsaid squared shaft end 6211 Without movement of the "rack bar, which'is desirablein e'fl'ecting' adjustment of the spring in thie factory: whenthe springis given the"desired adjustment, and before'releasing it, the-'rack'bar is moved into -mesh withthe gear,the bearing rod 6-! 'is moved to the right hand ends of the slots 69, thus" moving the roller 66'to its operative position adj acent the web 64a, the pins 10 are inserted to hold'the rod 61in place, the spring" is released, and the cabinet is ready for use;

The'rollerGG has a length substantially equal to the spacing'ofthe side legs'of'the member 68 from *eachother; which serves to retain'the rack bar 64 laterally in-alignment with the gear 63'.

Adjacent to and below'th'e mounting'rnember 6!; the spring casing 59 has rigidly'securedthereto, a-small'mountingplate 1 l 'ri'gidly'supporting stud rods '12 and 13 extending from saidplate parallel-with the rod S'Lwhich stud rods serve respectively as a' pivotal supportfor the upper end portion of a detent'a'rm' wand as'a fixed support for one end portion of a flat spring 15 pressing at its opposite 'end portion'against said detent arm (see Figs. 1*, 3"and 4)? The detent arm 14 may be held in place' on the 'rodl'fin any .shown' in Fig. 3, the roller lt is'held in lateral alignment with the web 6.4a by the supporting structure described, and ispressed'against the outer edge surface of said web with substantial pr ssu e y th s i was indicated inFig. 4. Y shown in Fig. 4;, the lower end portion of the web 64a is out out in the form of an arcuate recess or seat 18 of substantial depth receiving and loosely fitting the roller 16 when the cover I3 is in its fully opened or substantially vertical position as shown in Fig. l, at which time little or no downward thrust is exerted on the rack bar 64 by the gravity moment of the cover I3 around its hinges [4. As shown in Fig. 4, the seat 18 is continued downwardly by a tangent and oblique cam surface 73 for a desired distance, which cam surface at its lower enli terminates in an arcuate hook-shaped stop surface extending sufficiently around the roller 16 when the latter is in engagement with it, to positively prevent upward movement of the rack bar 64 relatively to the roller.

As a result of the construction just described, when the cover I3 is raised from its closed position, the roller 16 'rolls on the edge surface of the web 54a without opposing said opening movement to an appreciable extent, although the pressure of the roller on the web is substantial; this condition continues until'the cover reaches its vertical position, at which time the roller is forced by the spring 15 into engagement with the detent recess 18 in th'e'web, which detent recess is of substantially less depth than the radius of the roller 76, thereby permitting movement of the cover in either direction to'disengage the roller from the detent recess, by the' application of a corresponding force to the cover, which force is determined in amount largely by the strength of the spring 15, which strength should be substantial to insure substantial detent action by the roller 16.

When the cover 13 is carefully opened by the operator, the detent -action described limits said opening movement by engagement of the roller 76' with the detent recess l8 as described, and closing movement of 'the' cover will require the applicationof'an initial force which although appreciable, is not large enough to be objectionable; in some cases, however, by' careless operation, the cover may be opened too rapidly, developing considerable-'inertiabfmovement when the detent position of the'cover is reached, and in any such case the rack bar may be" moved beyond its detent position, thereby raising the roller on the cam surface 19 with progressively increasing spring resistance and cushioning action depending on the length and inclination of the cam surface, thus counteracting or'substantially reducing the inertia of movement of the cover by the time the roller engages the stop surface 80 on the rack bar, and thereby'reducing the shock of engagement of the roller withthe stop surface. The cam surface 18 should have such inclination to the roller", and'th'e spring 15 should be of sufficient' strength for the stopping position of the rack bar, to move the cover and rack bar from their stopping position, forwardly to their detent position-sothat closing movement of the cover may then proceed in a normal manner. The counterb'alancing structure described in connection'with Figs. 1 to 5 inclusive is preferablyenc'lose'd bya removable casing 8|, which, when in place on thecabinet, prevents access to the shaftendfla and to the pins 10, thereby preventing the unauthorized adjustment of the spring 60; The casing may be secured to the cabinet; in any' convenient'manner, for example by suitable'screws.

The counterbal'ancing structure described in connection with Figs. 1 to 5 inclusive may, if preferred, be mounted in'the "side walls of the cabinet, Where'sa'id walls are'bf sufiicient thickness to perr'nitso doing, and where complete heat insulation of the cabinet is not required, in which case it is desirable to provide said side walls with doors affording access to the shafts'62 and to the pins 10 for the spring adju-stingpurposes described.

The counterbalancing structure described in connection with Figs. 1 to 5 inclusive, is preferably duplicated on the other side wall of the cabinet l3, the only difference being that the parts have an opposite hand relation when viewed from said other side.

The metal parts of the above counterbalancing structure shown and described as having fixed connection with each other, maybe secured together in any convenient manner, for example, by screws, bolts, or by welding. p

The spiral spring 60 may be replaced by a similar and equivalent spring developing an increasing stress therein by the closing movement of the cover, accompanied by a decrease in the number of turns of said spring, by reversing the direction of the spiral of said spring indicated in Fig. 1, and constructing said spring to be relatively closely'wound for its condition of minimum stress.

It will be understood that for'cabinets of the kind described, the counterbalancing structures should be of substantial construction, since, for example, the covers of planfiles of large size weigh 300 pounds or more.

It is desirable with the counterbalancing structure shown, that one of said structures be employed in or on each of the opposite side walls of the cabinet, and that the two said structures shall be of substantially the same construction and'have equal counterbalancing effects in any case; this arrangement has two advantages, first, it eliminates the possibility of twisting and racking the cover and producing unbalanced forces on the hinges, and second, in the event of breakage in one of the counterbalancing structures, the other of said structures avoids the danger of serious accident.

It should, however, be noted, that the invention is operative where only one of said counterbalancing structures is used with a hinged cover, which arrangement may be satisfactory for many cabinets and particularly for those having hinged covers of relatively small size and weight, by proportioning the single counterbalancing structure to counterbalance to a desired degree the entire gravity moment of the cover around its hinges.

The weight of the cover i3, which is large for cabinets of large size and requires some form of counterbalancing to permit it to be easily moved from its closed to its open position, exerts a turning moment by gravity around the hinges It during its opening movement, which opposes said opening movement and which is a cosine function of said opening movement; and the spring 60 exerts a thrust on the link or rack bar 64, in opposition to the thrust exerted on said rack bar by said gravity moment, and develops a stress in the spring which increases for closing movement of the cover and which decreases for opening movement of the cover, the change in stress in the spring bein proportional to the deflection of the spring from one position of the cover to another, said deflection being the change produced in the number to turns or convolutions of the spring by movement of the cover from one position to the other.

The result of the expressed relations to each other of the cover l3, rack bar 64 and spring 60,

, 6 isthat the counterbalancing thrust exerted'upwardly on the rack bar 64 by the spring 60 during cover movement in either direction,,parallels and is similar in degree tov the downward thrust on the rack bar 64 exerted by the gravity moment of said cover around its hinges during its said movement, thereby providing for any desired differential between said upward and downward thrusts on the rack bar 64 by correspondingly proportioningand adjusting the spring 60.

The lifting thrust exerted on the rack bar 64 by the spring 60 should be somewhat less than the downward thrust exerted on the rack bar by the gravity moment of the cover for any position of the cover, for otherwise the cover will not tend to move to its closed position nor to stay in that position; the uncounterbalanced portion of the gravity moment of the cover must, of course, be overcome by the operator of the cabinet, but this manual effort can readily be reduced by the counterbalancing devices described so that it is not burdensome.

In the claims, the term deflection of a recited spring, is used toinclude a change in the number of turns with corresponding change in stress of said spring'of the spiral type.

While I have shown 'my invention in the particular embodiment above described, I do not limit myself thereto'as I may employ equivalents thereof without departing from the scope of the appended claims. I

What I claim is:

1. Means for counterbalancing the hinged covers of cabinets, including a cabinet having enclosing side walls and an open upper end, a cover hinged at one edge toone of said walls and movable to open and close said upper end, a link pivotally connected at its upper end with said cover and extending downwardly therefrom adjacent one of said side walls, spring means connected with the lower portion of said link and stressed by closing movement of said cover, said link having rack teeth in one of its surfaces, and said spring means including a spiral spring held at one end by a fixed support, and a gear secured to the other end of said spring and meshing with said rack teeth, the toothed surface of said link having a longitudinal curvature, a roller engaging a surface of said link opposed to said toothed surface and holding said rack teeth in mesh with said gear, said roller having a bearing rod projecting from its ends, a U-shaped bearing member with slots in its side legs supporting the ends of said bearing rod, said slots extending away from said link and having a length substantially greater than the diameter of said bearing rod, and movable means holding said bearing rod in a position in said slots effecting a meshing engagement of said rack teeth with said gear, whereby moving said movable means to rod-releasing position permits moving said rack teeth from engagement with said gear for spring adjusting purposes.

2. Means for counterbalancing the hinged covers of cabinets, including a cabinet having enclosing side walls and an open upper end, a cover hinged at one edge to one of said walls and movable to open and close said upper end, a link pivotally connected at its upper end with said cover and extending downwardly therefrom adjacent one of said side walls, spring means connected with the lower portion of said link and stressed by closing movement of said cover, and a spring actuated detent having fixed support and engaging said link, said link having a recess yieldingly engaging said detentfor .the open position of saidcov er, wherebys'aidcover in its open position is yieldingly held against movement, said link having .a projecting surface extending from its saidrecjess for engagement by said detent and also a .stop surface,'whereby cover opening movement from its detent-held position is resisted by engagement of said detent with said cam surface and stopped by engagement of said detent with said stop surface.

3. Means for ,counterbalancing the hinged .covers of cabinets, including a cabinet having enclosing side walls and an open upper end, a cover hinged at one edge to one of said walls and movable to open and ,close said upper ,end, a link pivotally com ected at its upper end with said Cover and extending downwardly therefrom adjacent one of said side walls, spring means connected with the lower portion of said link and stressed by closing movement of said cover, said link having rack teeth in one of its surfaces, and said spring means including a spiral spring held at one end by a fixed support, and a gear secured to the other end of sa'id'spring and meshing with said rack teeth, said spring having a relation to said gear increasing the deflection of said spring for closing movement of said cover, and a spring actuated detent having fixed support and engaging said link, said link having a recess yieldingly engaging said detent for the open position closing side walls and an open upper end, a cover hinged at one edge to one of said walls and movable to open and close said upper end, a link pivotally connected at its upper end with said cover and extending downwardly therefrom adjacent one of said side walls, :spring means connected with the lower portion of said link and stressed by closing movement of said cover, said link having rack teeth in one of its surfaces, and said spring means including a spiral spring held at one end by a fixed support, and a gear secured to the other end of said spring and meshing with said rack teeth, said spring having a relation to said gear increasing the deflection of said spring for closing movement of said cover, and a spring actuated detent having fixed support and engaging said link, said link having a recess yieldingly engaging said detent for the open position of said cover, whereby said cover in its open position is yieldingly held against movement, said link having a projecting cam surface extending from its said recess for engagement by said detent and also a stop surface, whereby cover opening movement from its detent-held position is resisted by engagement of said detent with said cam surface and stopped by engagement of said detent with said stop surface.

CHARLES B. ULRICH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,314,950 Desmond Sept. 2, 1919 1,324,600 Levanseler Dec. 9, 1919 2,213,319 Lickteig Sept. 3, 1940 2,269,251 Carson Jan. 6, 1942 2,325,897 Waltman Aug. 3, 1943 FOREIGN PATENTS Number Country Date 502,095 Great Britain Mar. 10, 1939 

